Lightweight constructional element with external ribbing

ABSTRACT

A lightweight constructional element ( 100 ) is disclosed. The lightweight constructional element ( 100 ) comprises: (a) a shell-shaped basic body or shell ( 1 ), e.g., fabricated from metal, having interior ( 20 ) and exterior ( 23 ) surfaces, the interior surfaces ( 23 ) of the basic body define an interior space ( 26 ); and (b) reinforcing ribs ( 2   a,    2   b ) of plastics material, preferably thermoplastic material, which are fixedly attached to the exterior surface ( 23 ) of basic body ( 1 ). The reinforcing ribs are fixedly attached to the exterior surface of said basic body by means of discrete attachment points {which may include, for example, apertures ( 3   a ), slots ( 3   f ), beads ( 3   b ) and/or protrusions ( 3   c )}. Articles of manufacture that may include the lightweight constructional element include, for example, structural components of motor vehicles (e.g., a cross car beam) and aircraft, and a structural component having a channel for receiving at least one of a cable and a gas.

CROSS REFERENCE TO RELATED PATENT APPLICATION

[0001] The present patent application claims the right of priority under35 U.S.C. §119 (a)-(d) of German Patent Application No. 102 08 953.1,filed Feb. 28, 2002.

FIELD OF THE INVENTION

[0002] The invention relates to a lightweight constructional elementcomprising a shell-shaped basic body, in particular of metal, havingreinforcing ribs of plastics material, in particular of thermoplasticplastics material, which are permanently fixed to the basic body.

BACKGROUND OF THE INVENTION

[0003] Stiff, high-strength lightweight structural elements withinternal ribbing already exist in what is commonly referred to as“hybrid technology” (generally, a technology involving the combinationof metal inserts with thermoplastic plastics material). For reasons ofspace constraints, however, such structures do not meet the requirementsassociated with integration of additional components and application(e.g., conduits for wiring and air transport, and other channels, withinthe interior of the basic body).

[0004] Previously, instrument panel supports or so-called cross-carbeams or cross-members in motor vehicles have been produced from steeltubing with various welded-on or screwed-on parts. These parts haverelatively high weight. Moreover, with these elements theabove-mentioned direct molding-on of further constructional elements tothe basic body using the injection-molding process is impossible orpossible only with difficulty.

[0005] EP 370 342 A1discloses a lightweight constructional elementconsisting of a shell-shaped profile section with internal supportingribs consisting of molded-on thermoplastic plastics material. Althoughthis constructional element may be used as a support structure, inparticular in the form of plastics-metal composite bodies, its furthertechnical application as a constructional element is typically limited.

[0006] It is an object of the invention to develop a lightweightconstructional element which is relatively simple to manufacture and hasgood physical properties, such as high stiffness and strength. Such anewly developed lightweight constructional element preferably consistsof one or optionally a plurality of (shell-shaped) basic bodies. It isdesirable that the basic bodies of such newly developed lightweightconstruction elements must provide channels for wiring or air transport,and further applications. It is further desirable that such newlydeveloped lightweight construction elements have a level of stiffnessthat is at least comparable to that of prior art structures, such asmetal tube cross-car beams.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, there is provided alightweight constructional element (100) comprising:

[0008] (a) a shell-shaped basic body or shell (1), e.g., fabricated frommetal, having interior (20) and exterior (23) surfaces, the interiorsurfaces (23) of said basic body defining an interior space (26); and

[0009] (b) reinforcing ribs (2 a, 2 b) of plastics material, preferablythermoplastic material, which are fixedly (or permanently) attached tothe exterior surface (23) of said basic body (1),

[0010] wherein said reinforcing ribs are fixedly attached to theexterior surface of said basic body by means of discrete attachmentpoints {which may include, for example, apertures (3 a), slots (3 f),beads (3 b) and/or protrusions (3 c)}, said reinforcing ribs being oneof directly and indirectly fixedly attached to the exterior surface ofsaid basic body.

[0011] The features that characterize the present invention are pointedout with particularity in the claims, which are annexed to and form apart of this disclosure. These and other features of the invention, itsoperating advantages and the specific objects obtained by its use willbe more fully understood from the following detailed description andaccompanying drawings in which preferred embodiments of the inventionare illustrated and described.

[0012] Unless otherwise indicated, all numbers or expressions, such asthose expressing structural dimensions, quantities of ingredients, etc.used in the specification and claims are understood as modified in allinstances by the term “about.”

[0013] As used herein and in the claims, the term “perforation” means ahole of any size or configuration, typically present in the basic body(1) and optionally the flanges (8) of the basic body, and includes, butis not limited to, apertures and/or slots.

[0014] As used herein and in the claims, the term “aperture” means aperforation having substantially similar cross dimensions, and includes,but is not limited to shapes selected from substantially circular,substantially square, and/or substantially triangular.

[0015] As used herein and in the claims, the term “slot” means aperforation that is generally elongated in one dimension relative to theother dimension(s) of the perforation, and includes, but is not limitedto, rectangular slots and elliptical slots.

[0016] As used herein and in the claims, and unless otherwise noted, theterm “plastics material” means thermoplastic materials (plasticsmaterials that are substantially free of a 3-dimenstional crosslinknetwork) and/or thermoset plastics materials (plastics materials having3-dimensional crosslink network).

[0017] As used herein and in the claims, the term “directly fixedlyattached” with regard to the exterior reinforcing plastic ribs meansthat the reinforcing ribs are form- and force-closed connected to thebasic body by means of apertures or slots.

[0018] As used herein and in the claims, the term “indirectly fixedlyattached” with regard to the exterior reinforcing plastic ribs, meansthat the reinforcing ribs are force-closed connected to the basic bodyby means of beads or protrusions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a representative perspective side view of asubstantially closed lightweight constructional element (103) accordingto the present invention, which includes a cover plate (5 a);

[0020]FIG. 2 is a representative perspective side view of an openlightweight constructional element (100) according to the presentinvention, which includes substantially laterally outwardly extending(or doubly angled) reinforcing flanges (8);

[0021]FIG. 3 is a representative section through a closed profilesection of substantially closed lightweight constructional element (105)that is similar to that of FIG. 2; and

[0022]FIG. 4 is a representative section through a lightweightconstructional element (107) similar to that of FIG. 3 having aperturesin the basic body and in the cover plate.

[0023] In FIGS. 1 through 4, like reference numerals designate the samecomponents.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In an embodiment of the present invention, the basic body isfabricated from a material selected from at least one of thermosetplastics material, thermoplastic materials and metal. In a furtherembodiment, the plastics material of the reinforcing ribs is selectedfrom at least one of thermoset plastics material and thermoplasticmaterials.

[0025] The connection between the reinforcing ribs and the basic body ispreferably effected at or by means of perforations (e.g., aperturesand/or slots) through which the plastics material passes and extendsbeyond the plane of the perforations (e.g., apertures and/or slots).

[0026] Increased or improved stiffness of the constructional element maybe obtained in a preferred embodiment of the present invention when theconnection between the reinforcing ribs and the basic body isadditionally effected by means of at least partially encasing the rimportions of the basic body by means of plastics material. Moreparticularly, in an embodiment of the present invention the basic bodyof the lightweight constructional element has a shape selected fromsubstantially U-shapes and substantially V-shapes each having twosidewalls (e.g., substantially opposed sidewalls), each sidewall havinga rim, and the reinforcing ribs are further fixedly attached to theexterior surface of the basic body by means of plastic material of theribs at least partially encasing the rims.

[0027] In a preferred embodiment of the present invention, thelightweight constructional element is given still greater stiffness ifthe basic body has in its rim portion an angled reinforcing flange, inparticular a doubly-angled reinforcing flange. More particularly, thebasic body of the lightweight constructional element has a shapeselected from substantially U-shapes and substantially V-shapes eachhaving two sidewalls (e.g., substantially opposed sidewalls), eachsidewall having a substantially laterally outwardly extending flange(e.g., an angled reinforcing flange), and said reinforcing ribs arefurther fixedly attached to the exterior surface of the basic body bymeans of the plastic material of the ribs at least partially encasingthe flanges.

[0028] These angled rim portions (or laterally outwardly extendingflanges) of the basic body can be variously formed (e.g., in accordancewith the deep-draw process of the metal part), and their configurationsare, for example, primarily determined by the design requirements of theconstructional element as a whole.

[0029] The lightweight constructional element is particularly simple tomanufacture but also simple to detach (e.g., separate the reinforcingribs from the basic body or shell) for the purposes of plastics materialrecycling, if the connection between the reinforcing ribs and the basicbody is effected by means of the plastics material molded onto theexterior surfaces of the basic body, e.g., by means of theinjection-molding technique, as will be discussed in further detailherein.

[0030] In a particularly preferred embodiment, to further increase thestrength of the lightweight constructional element, the exterior surfaceof the basic body ( in addition to the reinforcing ribs) is encased withplastics material. The exterior encasing plastics material mayoptionally be continuous with the plastics material of the exteriorreinforcing ribs.

[0031] Particularly advantageous with respect to corrosion protection,e.g. of metal inserts, is a preferred lightweight constructional elementof the present invention, in which the interior surfaces of the basicbody are at least partially encased in plastics material. The interiorencasing plastics material may optionally be continuous with theplastics material of the exterior reinforcing ribs that extends throughperforations in the basic body into the interior space of the basicbody, and thereby serving to further fixedly attach the exteriorreinforcing ribs to the exterior surface of the basic body.

[0032] The spatial form of the shell of the lightweight constructionalelement can be freely selected, depending on the application. Apreferred constructional form of the lightweight constructional elementis characterized in that the the basic body has a shape is selected fromsubstantially U-shapes and/or substantially V-shapes (relative to theprofile section of the basic body).

[0033] The advantage of the basic body of the present invention, ascompared to closed box-section basic bodies, lies in the greatersimplicity of its manufacture, e.g., by means of the extrusion process.

[0034] To form wiring or air conduits the shell-shaped basic body mayoptionally be closed with a cover plate. A lightweight constructionalelement is therefore preferred which is characterized in that at leastone additional cover plate enclosing the interior space of the basicbody at least partially, and in particular completely, is attachedacross (or over) the interior space of the basic body. In an embodimentof the present invention, the basic body has a shape selected fromsubstantially U-shapes and substantially V-shapes each having twosidewalls, each sidewall having a substantially laterally outwardlyextending flange, the lightweight constructional element furtherincludes a cover plate, which is fixedly attached to each of the flangesand covers at least a portion of the interior space of the basic body.

[0035] The cover plate can project in any desired manner beyond the sideportions (or sidewalls) of the lightweight constructional element. Inwhich case it may then optionally contain further functional elementssuch as dashboard parts, etc., and can therefore serve as a furtherdesign feature.

[0036] In a particularly preferred form of the lightweightconstructional element of the present invention, the cover plate isjointly encased by plastics material in the rim portion of the basicbody to close the interior space. In an embodiment, the cover plate isfixedly attached to the basic body by means of plastics materialencasing each of the flanges and at least a portion of the cover platethat abuts (or is at least superposed over) each of said flanges.

[0037] The stiffness of the constructional element can be furtherincreased if the cover plate is preferably combined with the basic bodyby means of apertures or slots arranged one above the other, throughwhich the plastics material passes and extends beyond the plane of theapertures or slots. A kind of riveted plastics connection is therebyproduced. In an embodiment of the present invention, each of the coverplate and the flanges have a plurality of perforations, each perforationhaving a plane, at least some of the perforations of the cover plate andflanges are aligned with each other, the aligned perforations form aplurality of aligned perforations each having a plane, the cover plateis fixedly attached to the basic body by means of plastics materialextending through and beyond the plain of least some of the alignedperforations. The perforations of the aligned perforations may beselected from apertures and/or slots.

[0038] If an airtight channel is required, the connection between theclosure plate and the shell-shaped basic body or the lightweightconstructional element may be effected by means of a welded or bondedjoint, and/or an additional sealing element such as a rubber seal may beinserted.

[0039] For certain applications (e.g., air conduit, etc.) a preferredlightweight constructional element is advantageous which ischaracterised in that the attachment point of the cover plate to thebasic body is closed in an airtight manner by means of a welded orbonded joint or by means of a sealing agent, in particular a rubberseal. The cover plate, in an embodiment of the present invention, formsan airtight seal over the interior space of the basic body by means of awelded joint, a bonded joint and/or a sealing agent positioned betweeneach of the flanges and at least a portion of the cover plate that isfixedly attached to each of the flanges.

[0040] A preferred form of the lightweight constructional element inwhich the interior of the basic body has at least one dividing wall, inparticular of thermoplastic plastics material, has proved successful inseparately accommodating a plurality of conduits.

[0041] Sheet metal, preferably steel or aluminum sheet, diecast metal,in particular aluminum, zinc or magnesium, or fiber-reinforced plasticsmaterial or composite material may be used as the preferred material forthe basic body and optionally the cover plate of the lightweightconstructional element.

[0042] As a preferred material for the reinforcing ribs and optionallythe encasement of the lightweight constructional element, a plasticsmaterial selected from the series: polycarbonate, polyester, inparticular PET or PBT, polyurethane, polystyrene, polyamide,polyalkylene, in particular polypropylene, is used.

[0043] Lightweight, structural and housing elements with highfunctionality find application in the vehicle industry, in mechanicalengineering and the appliances industry, in the electrical industry andin other constructional elements.

[0044] In particular, these elements can be used in the vehicle industryas instrument panel supports or so-called cross-car beams (CCBs).

[0045] If applicable, further constructional elements such as trim orfunctional parts for the dashboard area can be directly molded on to theexterior areas of the basic body or the ribbing, using theinjection-molding process.

[0046] Manufacture of the above-mentioned lightweight structuralelements is possible in a reasonable manner with a relatively shortproduction time, especially using the injection-molding process. In apreferred embodiment of the present invention discrete attachment pointsinclude a plurality of perforations, a plurality of beads and/or aplurality of protrusions. The reinforcing ribs are preferably fixedlyattached to the outer surface of the basic body by means of a process ofmolding plastics material onto the exterior surface of the basic body,the molded-on plastics material at least one of: (i) extends through atleast some of the perforations and into the interior space of the basicbody; (ii) fills at least some of the slots; (iii) fills at least someof the beads; and (iv) encases at least partially at least some of theprotrusions. The process of molding plastics material onto the exteriorsurface of the basic body includes: (i) injection-molding (in the caseof thermoplastic, materials): (ii) reaction-injection-molding (in thecase of thermoset plastics materials, such as 2-pack thermoset orthermosetable polyurethane compositions); and (iii) a combination ofinjection-molding and reaction-injection-molding (in the case ofplastics compositions that include both thermoplastic materials andthermoset plastic materials or components).

[0047] The invention therefore further relates to the application of alightweight constructional element according to the invention as astructural component or support structure for motor vehicle or aircraftconstruction, in particular as a support structure with a channel forwiring or gas, particularly preferably with an air channel, andparticularly preferably as an instrument panel support or cross-carbeam. Articles of manufacture that may include the lightweightconstructional element of the present invention include, but are notlimited to: a structural component of a motor vehicle; a structuralcomponent of an aircraft; and a structural component having a channelfor receiving at least one of a cable and a gas. Further articles ofmanufacture that may include the lightweight constructional element ofthe present invention include, but are not limited to: an instrumentpanel support; and a cross-car beam.

[0048] In a particularly preferred embodiment of the present invention,the reinforcing ribs, of the lightweight constructional element, form acontinuous unitary structure on the exterior surface of the basic body.

[0049] The invention is described in further detail below, in anexemplary manner, with reference to the drawing figures.

EXAMPLES Example 1

[0050] A U-shaped profile section (basic body or shell) 1 of sheet steel(thickness 0.8 mm) with angled flanges 8 (in the rim region 29) isprovided on its exterior with cruciform ribs 2 a of thermoplasticplastics material (e.g., of glass-fiber reinforced PA 6). The ribbing ismolded on to the profile section using the injection-molding process, asdescribed previously herein. Disposed across the interior of the profilesection 1 is a cover 5 a which is permanently fixed to the rim 8 of theprofile section 1 by means of a molded rim encasement 4.

[0051] At certain points of its surface the profile section 1 hasperforations in the form of apertures 3 through which the thermoplasticmaterial passes. The plastics material here forms a riveted connection 3a similar to that depicted in FIG. 3. The profile section 1 according toFIG. 1 forms part of a heated air conduit.

Example 2

[0052]FIG. 2 represents a profile section 1, similar to that of Example1, in which the profile section 1 has doubly-angled reinforcing flanges8. Here the lateral reinforcing ribs 2 b are disposed perpendicularlywith respect to the extension and flanges of the profile section.

[0053] The ribs 2 b are attached at profile section slots 3 f by meansof thermoplastic material passing through the profile section 1. Herethe profile section is formed as an open box section.

Example 3

[0054] In the metal profile section 1 shown in FIG. 3 the internalsurfaces 20 are encased by thermoplastic plastics material 9, which canbe seen in cross-section. Similarly to that depicted in FIG. 1, theprofile section 1 has a cover plate 5 a which is attached to the profilesection 1 by means of bonding agent 6.

[0055] In place of the bonding agent 6, attachment by a welded edgejoint can also be provided (not shown). In case of a welded joint thesame material/plastics material may be used for the cover plate as forthe adjoining interior encasement.

[0056] The cover plate 5 a is manufactured, in this case, fromglass-fiber reinforced thermoset material.

[0057] Three variants of attachment points are shown in cross-section inFIG. 3: a simple aperture 3 a, a trapezoidal bead 3 b, and ahemispherical protrusion 3 c.

[0058] The profile section 1 has doubly-angled flanges 8 which areencased in thermoplastic plastics material 4 and, in combination withthe attachment points 3 a, 3 b, 3 c, ensure the strength of thecomposite.

[0059] For further stiffening of the constructional element the coverplates 5 a may have reinforcing beads 7 disposed in a longitudinal,transverse or cruciform manner.

Example 4

[0060] In FIG. 4 a metal profile 1 is shown in cross-section, which hasexternal plastic ribbing 2 a, 2 b, similarly to the profile sectionaccording to Example 2. Here again, through the injection-moldingprocess, the thermoplastic material passes through the profile sectionbasic body 1 at the apertures 3 a, 3 e or the slots 3 f and formsattachment points.

[0061] Attached across the interior of the profile section 1 is a metalcover 5 b which is seated directly on the metal profile 1 and formstherewith an electrically shielded channel 26. Apertures 3 g in thecover 5 b are disposed directly above the apertures 3 e or slots 3 f inthe profile section 1 and are riveted by means of the plastics materialto the profile section 1.

[0062] In view of the angled flange portion of the basic body in FIG. 3,only longitudinal ribs 2 b of plastics material on the side areas of thebasic body, according to the direction of deformation, are consequentlynow possible as reinforcement.

[0063] The profile section also has over its entire exterior surface 23an outer encasement 10 of the same thermoplastic material as the ribs 2a, 2 b. In this case the attachment points 3 d, 3 e, 3 f do not need tobe located directly in the area of the ribs 2 a, 2 b.

[0064] The process of attaching a metal cover plate 5 b may be executeddirectly by the normal injection-molding process of the lightweightconstructional element or using the so-called“in-mold-assembly-process”, instead of a conventional joining process(bonding, welding 6).

[0065] Although the invention has been described in detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that variations can be madetherein by those skilled in the art without departing from the spiritand scope of the invention except as it may be limited by the claims.

What is claimed is:
 1. A lightweight constructional element comprising:(a) a shell-shaped basic body having interior and exterior surfaces, theinterior surfaces of said basic body defining an interior space; and (b)reinforcing ribs of plastics material which are fixedly attached to theexterior surface of said basic body, wherein said reinforcing ribs arefixedly attached to the exterior surface of said basic body by means ofdiscrete attachment points, said reinforcing ribs being one of directlyand indirectly fixedly attached to the exterior surface of said basicbody.
 2. The lightweight constructional element of claim 1 wherein saidbasic body is fabricated from a material selected from at least one ofthermoset plastics material, thermoplastic materials and metal.
 3. Thelightweight constructional element of claim 1 wherein the plasticsmaterial of said reinforcing ribs is selected from at least one ofthermoset plastics material and thermoplastic materials.
 4. Thelightweight constructional element of claim 1 wherein said discreteattachment points comprise at least one of: a plurality of perforations;a plurality of beads; and a plurality of protrusions.
 5. The lightweightconstructional element of claim 1 wherein said basic body has aplurality of perforations each having a plane, said reinforcing ribs arefixedly attached to the exterior surface of said basic body by means ofthe plastics material of said reinforcing ribs extending through atleast some of said perforations, extending beyond the plane of saidperforations and into the interior space of said basic body, saidperforations being selected from at least one of apertures and slots. 6.The lightweight constructional element of claim 1 wherein said basicbody has a shape selected from-substantially U-shapes and substantiallyV-shapes each having two sidewalls, each sidewall having a rim, saidreinforcing ribs are further fixedly attached to the exterior surface ofsaid basic body by means of plastic material of said ribs at leastpartially encasing said rims.
 7. The lightweight constructional elementof claim 6 wherein the rim of each sidewall has a substantiallylaterally outwardly extending flange, and said reinforcing ribs arefurther fixedly attached to the exterior surface of said basic body bymeans of plastic material of said ribs at least partially encasing saidflanges.
 8. The lightweight constructional element of claim 4 whereinsaid reinforcing ribs are fixedly attached to the outer surface of saidbasic body by means of a process of molding plastics material onto theexterior surface of said basic body, the molded-on plastics material atleast one of: (i) extending through at least some of said perforationsand into the interior space of said basic body; (ii) filling at leastsome of said slots; (iii) filling at least some of said beads; and (iv)encasing at least partially at least some of said protrusions.
 9. Thelightweight constructional element of claim 1 wherein the exteriorsurfaces of said basic body are at least partially encased in plasticsmaterial.
 10. The lightweight constructional element of claim 1 whereinat least a portion of the interior surfaces of said basic body areencased with plastics material.
 11. The lightweight constructionalelement of claim 1 wherein said basic body has a shape selected fromsubstantially U-shapes and substantially V-shapes.
 12. The lightweightconstructional element of claim 1 wherein said basic body has a shapeselected from substantially U-shapes and substantially V-shapes eachhaving two sidewalls, each sidewall having a substantially laterallyoutwardly extending flange, said lightweight constructional elementfurther comprising a cover plate, said cover plate being fixedlyattached to each of said flanges and covering at least a portion of theinterior space of said basic body.
 13. The lightweight constructionalelement of claim 12 wherein said cover plate is fixedly attached to saidbasic body by means of plastics material encasing each of said flangesand at least a portion of said cover plate that abuts each of saidflanges.
 14. The lightweight constructional element of claim 12 whereineach of said cover plate and said flanges have plurality ofperforations, each perforation having a plane, at least some of theperforations of said cover plate and said flanges are aligned with eachother, the aligned perforations forming a plurality of alignedperforations each having a plane, said cover plate being fixedlyattached to said basic body by means of plastics material extendingthrough and beyond the plain of least some of the aligned perforations,said perforations being selected from at least one of apertures andslots.
 15. The lightweight constructional element of claim 12 whereinsaid cover plate forms an airtight seal over said interior space of saidbasic body by means of at least one of a welded joint, a bonded jointand a sealing agent positioned between each of said flanges and at leasta portion of said cover plate that is fixedly attached to each of saidflanges.
 16. The lightweight constructional element of claim 1 furthercomprising at least one dividing wall positioned within the interiorspace of said basic body.
 17. The lightweight constructional element ofclaim 12 wherein said basic body and said cover plate are eachindependently fabricated from at least one material selected from thegroup consisting of sheet metal, diecast metal and fiber-reinforcedplastics material.
 18. The lightweight constructional element of claim 1wherein the plastics material of said reinforcing ribs is athermoplastic material selected from at least one of polycarbonate,polyester, polyurethane, polystyrene, polyamide and polyalkylene.
 19. Anarticle of manufacture comprising the lightweight constructional elementof claim 1 wherein said article is selected from: a structural componentof a motor vehicle; a structural component of an aircraft; and astructural component having a channel for receiving at least one of acable and a gas.
 20. An article of manufacture comprising thelightweight constructional element of claim 1 wherein said article isselected from: an instrument panel support; and a cross-car beam. 21.The lightweight constructional element of claim 1 wherein saidreinforcing ribs form a continuous unitary structure on the exteriorsurface of said basic body.